Pelvis, pelvic girdle and hip region

Question 1

What are the functions of the pelvis and hip joint?

Answer 1

Weight-bearing in standing and sitting, locomotion

Question 2

what does the pelvis comprise?

Answer 2

pelvic girdle (two hip bones) and sacrum

Question 3

what are the components of the hip bone?

Answer 3

Ilium, ischium and pubis

Question 4

what holds together the components of the hip bone?

Answer 4

triradiate cartilage

Question 5

what joints is the hip bone involved in?

Answer 5

sacroiliac joint, pubic symphysis, hip (coxal) joint

Question 6

what are the two parts of the sacroiliac joint and what do they articulate?

Answer 6

Fibrous syndesmosis: iliac tuberosity with sacral tuberosity and attachment of sacroiliac interosseous ligament

synovial plane joint: iliac and sacral auricular surfaces

Question 7

What is sacral nutation?

Answer 7

Body weight forces the base of the sacrum anteriorly and inferiorly. Ground reaction forces the apex posteriorly and superiorly. This results in the anterior tilt of the sacrum relative to the ilium (known as sacral nutation)

Question 8

What is the pubic symphysis comprised of?

Answer 8

Pubic bone articular surfaces lined by hyaline cartilage, interposed by fibrocartilage disc

Question 9

What type of joint is the hip joint?

Answer 9

synovial ball and socket multiaxial diarthrosis (can perform movement in 3 planes)

Question 10

What are the parts of the acetabulum?

Answer 10

Lunate surface (crescent shaped) is the weight bearing surface and is covered in articular cartilage. The acetabular fossa is the depression in the centre and it is non weight bearing. The transverse acetabular ligaments replaces the lunate inferiorly

Question 11

What is the frontal plane alignment of the femur?

Answer 11

Femoral angle of inclination: the angle formed between the neck of the femur and its shaft (normal is about 125-135 degrees)

Question 12

What is the transverse plane alignment of the femur?

Answer 12

Femoral anteversion: angle formed between the neck of the femur and condyles (normal is 15 degrees) ante = forwards

Question 13

Describe the hip joint alignment.

Answer 13

The head of femur and acetabulum both project anteriorly, therefore femoral head is directed toward anterior-superior acetabulum. This causes an exposed femur head surface in standing. This results in greater hip flexion ROM than hip extension ROM. During flexion and abduction, the. head of the femur is moved deeper into the acetabulum

Question 14

What are the consequences of femur angle of inclination and hip joint alignment?

Answer 14

Joint reaction force is more vertical on the neck of femur which places bending moment on NOF, creating tension on the lateral side and compression of the inferior side.

Question 15

What is the differences between coxa valga and coxa vara?

Answer 15

Coxa valga = lateral orientation of the shaft of femur relative to NOF (>135 degrees)
COxa vara = medial orientation of the shaft of femur relative to NOF (<120 degrees)

Question 16

What are the consequences of coxa valga and coxa vara alignment of the femur?

Answer 16

Coxa valga: Joint reaction force is more compressive along NOF, glut med moment arm is reduced (therefore more muscle fibres of other hip abductors need to be recruited), and orientation of head of femur is directed more superiorly

Coxa vara: Exposes greater bending moment therefore greater shear force, glut med moment arm is greater therefore increases efficiency of force produced by muscle, orientation of the head of femur is more medial and deep

Question 17

What are the hip flexor muscles (and what are the most effective of these)?

Answer 17

Psoas, iliacus and rectus femoris (most effective hip flexors)
Others include: Tensor fascia latae, sartorius (sartorius is also pretty effective), adductor longus, pectineus

Question 18

What are the functions of iliacus and psoas major?

Answer 18

Hip flexion. As well as this, when they contract they produce a posterior force on the anterior aspect of the femoral head which maintains the position of the femoral head in the acetabulum during hip flexion.

Question 19

What are the hip extensors? (mention which ones are most efficient)

Answer 19

Most efficient hip extensors include gluteus maximus, long head of biceps femoris, semitendinosus and semimembranosus. Adductor magnus also has a component that contributes to this action.

Question 20

What are the abductors of the hip?

Answer 20

Gluteus medius (main abductor; most torque produced), gluteus minimus, TFL, (sartorius can produce abduction but not much torque produced)

Question 21

What are the hip adductors?

Answer 21

Pectineus, adductor brevis, adductor longus, adductor magnus, gracilis

Question 22

What are the hip lateral (external) rotators?

Answer 22

Most efficient = gluteus maximus and posterior gluteus medius in hip extension)
Others include piriformis, obturator internus, superior gemellus, inferior gemellus, quadratus femoris, obturator externus

Question 23

What are the medial (internal) rotators of the hip?

Answer 23

There are no dedicated hip medial rotators (no muscle’s main action is to internally rotate the hip). However, in hip flexion, all of gluteus med and min; piriformis. In hip extension, anterior glut med and min, semimebranosus and semitendinosus

Question 24

What are the actions of the different segments of gluteus maximus?

Answer 24

all segments = hip extensors + hip lateral rotators
upper segments = hip abductors
lower segments = hip adductors

Question 25

What is an example of muscles that act differently in different ranges of motion?

Answer 25

Adductor magnus is also a hip extensor ALWAYS
Adductor longus and brevis are hip flexors when in natomical position, and hip extensors at 90 degrees flexion of the hip

Question 26

What nerves arise from the lumbar plexus?

Answer 26

Femoral nerve (L2-L4) and obturator nerve (L2-4)

Question 27

What structures form the femoral triangle?

Answer 27

Base = inguinal ligament
medial border = medial edge adductor longus
lateral border = medial edge sartorius
floor = iliopsoas, pectineus, adductor longus
apex = adductor canal

Question 28

What nerves arise from the sacral plexus?

Answer 28

superior gluteal nerve (L4-S1)
inferior gluteal nerve (L5-S2)
sciatic nerve (L4-S3) - combination of tibial nerve and common fibular nerve